The original shading looks better to me, becasue shape > shading. It looks very good, and i don't see something wrong or room for improvement. It's perfect.

I only wonder how's the background. If background has black contours too, it could be hard to notice the sprite because contour is thin, which seems a general problem with bringing old school pixel art to modern high resolutions.
Solution could be to use colored contours for the background (with similar color than the shaded surface just a bit darker) and reserving black for important stuff, or eventually make sprite contours 2 pixels wide.

In any case there is nothing to criticize without context of backgrounds to me.

@TheLuckyDonut Hey there, nice work!

Since it seems like a cartoony/cute style, I might try using a more saturated color for the shaded areas to liven it up.

And put it into the background/environment as soon as possible, since colors and values will appear different to the eye depending on what's around it, you probably won't arrive at the final look that is best for you until you put it into an environment.